You can tell a lot by someone's body language.
You get to know them, and all about their family, their aches and pains. Sometimes you laugh with them, sometimes you cry with them.
It really gets your blood going in the morning.
I never take anything personally. If they don't respond, I figure it's because of what's going on in their own life; they're preoccupied. I just try to help them with what I can.